Zapier is absolutely not a replacement for Rails. It is, however, all Matchist seems to pitch. I'm sure that they get a lot of clients asking for that sort of work, and that their projects are representative of that particular market. My point is, that's a market I have little interest in entering right now. Think of the difference between e.g. Pivotal Labs and the local "computer store" that advertises web development below networking and VOIP. I want someone to help push me towards the Pivotal Labs end of the spectrum. I don't need the opportunity to compete with other developers for low-value, low-skill work. I would like to pay for the opportunity to work on challenging, career-furthering projects that aren't the coding equivalent of "wham, bam, thank you RAM." That opportunity could take the shape of an agent.
I have two counterpoints in favor of the agent idea. Let's say I sign up with Al the Agent. Al's responsibilities can be roughly described as business development for an individual - i.e. me. I'd like it if Al could talk to me periodically, find out what I do and what I'd like to do, and keep putting opportunities for appropriate contract work in front of me. That's MVP. There's lots of room for improvement and other services, but MVP is literally someone else pounding the pavement. Now, to my counterpoints.
First, I don't care if Al has multiple developers. I only care that he can keep my pipeline full when I need it. Sports, film, television, music - all these other fields use agents, and those agents represent multiple clients in controlled ways. I don't care if Al represents 10 other developers, and in a way, I hope he does - it raises his profile (and, implicitly, mine). As long as he's still able to adequately meet my needs, I'm happy. If he starts pitching low-value WordPress theming (something I have no interest in), I'll sever the agreement. Even if this agency did turn into a Matchist-type service (which it needn't), that would not be a bad thing. As long as it doesn't turn into another boss, I'm happy.
Second, constant communication isn't really necessary. I can just talk to Al on a weekly basis, tell him what's going on, what I'd like to do, when I'll need more work, when I'm going to be on vacation, etc. That's not a taxing amount of communication, especially since I'm willing to make the economics work with a large percentage cut. I have a very limited amount of time I can put towards moonlighting (roughly 20 hours a week). If someone can help me do more profitable things (e.g. coding for money) with those hours, I'm happy to share the spoils. The common wisdom on HN is that a good developer can command somewhere around $100/hr for freelance work, which doesn't seem exaggerated since SV salaries can easily push $70/hr before benefits. If Al can get me 20 hours of work a week at $100/hr, I'm happy to cut him a big slice of that pie if he's willing to do that sort of communication.